Control apparatus for vehicles of the diesel-electric type



- Nov. 17, 1936. o, M E 2,060,900

CONTROL APPARATUS FOR VEHICLES OF THE DIESEL-ELECTRIC TYPE Fil ed Nov.30, 1932 v 3 Sheets-Sheet l a, 10 $2: 6 Y I l6 l9 i8 II 7 Q z z 2 z Nov.17, 1936. o. SIMMEN 2,060,900

CONTROL APPARATUS FOR VEHICLES OF THE DIESEL-ELECTRIC TYPE Filed Nov.50, 1932 3 Sheets-Sheet 2 flscar tfibrinen Nov. 17, 1936. Q, sl N2,060,900

CONTROL APPARATUS FOR-VEHICLES OF THE DIESEL-ELECTRIC TYPE Filed Nov.30, 1952 3 Sheets-Sheet 3 A; a J Rwfi W23, NCMB. T mm MA wa y 0? H 46 55. 5 m

Patented Nov. 17, 1936 UNITED STATES CONTROL APPARATUS FOR VEHICLES OFTHE DIESEL-ELECTRIC TYPE Oscar Simmen, Erlach, Switzerland, assignor tofirm Sulzer Freres Societe Anonyme, Win

thur, Switzerland ter- Application November 30, 1932, Serial No. 644,984

6 Claims.

This invention relates to control apparatus for vehicles of theDiesel-electric type having a Diesel-electric generating plant whichsupplies I current to the traction motor or motors of the vehicle. Theobject of the invention is to provide control apparatus forautomatically regulating the speed of the vehicle so as to maintain asubstantially uniform torque on the Diesel engine, at least in theregion of full torque.

According to this invention a variable resistance for the excitationcircuit of the generator which supplies current to the traction motors,is controlled automatically by the speed governor of the engine so thatthis resistance is inserted in the circuit whenever, on reaching thefull torque speed, the starting resistance controlled from the driverscab is switched out of the excitation circuit. The automaticallycontrolled resistance is then progressively cut outof the circuit underthe control of the governor as the speed of the vehicle increases.

The starting resistance, or a part thereof, may

' either constitute the resistance controlled by the engine governor orbe independent of that resistance. Preferably an isodromic return deviceis associated with the governor control mechanism so that the variableresistance remains set in any appropriate position when the governor isin its normal working position, for example, the full torque position.

The following is a description by way of example of one arrangement ofcontrol apparatus according to this invention with reference to theaccompanying drawings in which:

Figure 1 shows, somewhat diagrammatically, the arrangement of thegenerating plant and driving motors and the control apparatus therefor,

Figure 2 shows curves indicating the relation between the speed of thevehicle and the tractive effort, the voltage and the resistance tomotion,

and

Figures 3 to 7 inclusive show, also diagrammatically, modifications ofthe control apparatus shown in Figure 1.

As shown in Figure l a Diesel engine 1 drives a main electric generator2 which supplies current to the vehicle traction motors 3. The fieldcoil 8 of the main generator 2 is connected to an auxiliary excitationgenerator 4, also driven by the engine 8, by a circuit which includesthe conductor a starting resistance 65 and a. variable resistance i. Thefield coil i of the excitation generator is connected directly acrossthis generator. The value of the excitation curr nt of SwitzerlandDecember 4, 1931 the main generator can thus be controlled by movementof the operating lever ll of the variable resistance I or by acontroller III which is arranged to cut out the starting resistance 6 insteps which are lettered a -r and correspond respectively to the curvesa-r shown in Figure 2.

The position of the control lever I1 is controlled by the speed governorll of the Diesel engine I by means of operating mechanism comprising apower piston l5 acting in a cylinder I6 and connected to the lever I1,and a piston valve l4 having ports l8 and I9 respectively connected to asource of pressure fluid and to exhaust. The valve I4 controls thesupply of operating fluid for the power piston l5 and is connected to a-pivoted lever l3 which is operated by the sleeve I! of the enginegovernor H.

In Figure 2 the curves (1, b, c 1' show the relationships between thetractive effort (ordinate) and the speed c (abscissae) of the vehiclewhich correspond to successively increasing values of the excitationcurrent of the main generator. The curve E is the speed-voltage curve ofthe generator and the curve W the speedresistance to motion curve of thevehicle.

On starting the vehicle the resistance in the excitation circuit 01 thegenerator is cut out in steps which are such that the tractive effortdoes not exceed the value at which wheel slip willoccur and the tractiveeffort thus varies in the manner indicated by the curves Z1, Zk, Z1, Zm.When a vehicle speed, indicated at (01, is reached at which the fullpower of the Diesel engine is utilized, this speed being referred to asthe full torque speed, the remaining sections of the starting resistanceare rapidly cut out, and the control apparatus according to thisinvention is so arranged that the engine governor operates, immediatelyfollowing the cutting out of the remainder of the starting resistance,to introduce into the excitation circuit a variable resistance, which isof sufiicient value to prevent the engine being subjected to excessivetorque.

The governor then acts to cut out this variable resistance progressivelyas the speed of the vehicle increases, in such a. manner that the enginecontinues to operate at approximately full torque, the relationshipbetween the speed and the tractive effort being indicated by the curve Zin Figure 2. The tractive efiort is thus automatically controlled insuch a manner that the torque on the engine, which is a function of theproduct of the tractive effort Z and the speed 0, remains substantiallyconstant. It is to be noted that at any point on the curves of Figure 2the difference between the vehicle resistance curve W and the tractiveeffort curve Z shows the tractive eflort which is available foraccelerating the vehicle.

When the vehicle is started the Diesel engine is not subjected to fulltorque; hence the governor sleeve will be in its uppermost position andthe power piston i5 will be in its lowermost position, as shown inFigure 1, the resistance 1 being completely out out oi the excitationcircuit. During starting the steps a m ot the resistance 6, whichcorrespond respectively to the excitation curves a to m in Figure 2, aresuccessively cut out by the controller in and the vehicle attains its"full torque speed in. The steps n r are then rapidly cut out so thatmomentarily there is no resistance in the excitation circuit and theDiesel engine is subjected to excessive torque. The consequent downwardmovement of the sleeve l2 0! the governor ll below the full torqueposition causes the piston valve l4 to move downwardly thus admittingthe pressurefluid from the port It to the underside of the power pistonII and connecting the upper side of this piston to the upper exhaustport IS. The piston I5 then moves to its uppermost position thus movingthe lever I! to the position shown in chain lines in which the whole ofthe variable resistance 1 is in series in the excitation circuit.

The introduction of this resistance into the excitation circuit reducesthe output of the main generator so that the governor sleeve l2 risesto, or above, the full torque position. This raises the control valve I!so that the pressure fluid is cut off from the underside of the powerpiston i5 and, if the governor rises above the full torque position,pressure fluid is supplied to the upper side of this piston which thenmoves lever I! to reduce the effective value of resistance 1. As thespeed of the vehicle increases the torque on the engine decreases andthe governor operates in a manner that will be clearjrom the abovedescription to decrease the value of the variable resistance I. Thetractive eiTort and speed of the vehicle thus correspond to the curve Zin Figure 2 whilst the Diesel engine operates continuously atsubstantially full torque. The speed governor H may also control thesupply of fuel to the Diesel engine, or a separate governor may beemployed for this purpose. Thus, according to Fig. 1, the speed governorll actuates the fuel control lever 38 o! the fuel pump 39, whereas, inthe modification shown in Fig. 5, a separate speed-responsive device, orgovernor, II is provided for actuating iuel control lever 38, in orderto regulate the speed of the engine. It will be understood that thegovernor II operates to maintain the speed oi the engine constant withina predetermined range in the customary way.

In order to reduce hunting the control apparatus may be modified in themanner shown in Figure 3 by the provision 01 an isodromic" return orresetting device. When such a device is employed the power piston I5 isconnected to the piston valve H by the isodromic device 2Ii21 whichallows the piston l5 and consequently the lever H of the variableresistance 1 to remain set in any position so that the governor mayoccupy the same normal operating position, e. g., the full torqueposition, independently of the position of the piston IS.

The device 20-2'i comprises two cylinders 20 and 2| connected atopposite ends by passages and filled with any suitable liquid. Apiston22 in the cylinder 20 is connected by a pivoted lever 24 to the powerpiston l5, and a piston 23 in the cylinder 2| is connected to the end ofa floating lever 28 pivoted at its other end to the governor lever l3and at a point 29 between its ends to the piston valve I4. Springs 28and 21 normally maintain the piston 23 in its central position and aleakage hole" is provided in the piston 22 through which the liquidgradually flows as the piston 23 is returned by one 01 the springs 26and 21 to its normal central position following a movement thereofbrought about by movement 0! the piston 22. The device thus returns theend of the lever 28 to the normal position as shown in Figure 3independently of the position oi! the power piston is and the piston 22.

The upward movement of the power piston I5 following cutting out of thesteps 11 -4 01 the starting resistance, as described above, causesdownward movement of the piston 22 of the isodromic device and thusforces the piston 23 upwards against the spring 26. The floating lever28 is moved by the piston 23 to close the valve I 4. As the resistance 1is inserted in the excitation circuit the output of the generator isdecreased and the governor ll returns to its full torque position. Atthe same time the isodromic device has its piston restored to its normalcentral position by the spring 26 so that the piston valve I4 is kept inits closed position and the position of the power piston I! remainsunaltered.

If desired, the starting resistance can be controlled automatically, sothat the tractive effort is maintained below the value at which wheelslip occurs. In such an arrangement, as shown in Figure 4, an overloadrelay 30, in series in the circuit oi the traction motors 3, controls anoperating solenoid 3|, 32 for a valve 33. This valve is arranged betweenthe piston valve I4 and the power pistonli so that when the valve 33 isoperated, following operation of the relay 3!), it prevents pressurefluid being supplied to the upper side of the power piston l5 to movethis piston downwardly to cause a decrease in the value of theresistance 1 and thus an increase in the excitation current and in theoutput 01' the generator. The relay 30 is set so that it operates whenthe current supplied to the traction motors exceeds a predeterminedvalue above which wheel slip is likely to occur.

When required an additional governor 34 may be provided which is rotatedby a shai't 35 driven irom one of the axles of the vehicle. Thisgovernor serves to prevent the maximum speed of the vehicle, Umax inFigure 2, being exceeded and its sleeve 36 conveniently replaces thefixed pivot oi the lever 31 (H in Figures 1 and 3) controlled by theengine governor Ii. When the speed of the vehicle exceeds apredetermined value the governor sleeve 36 rises and the lever 31,pivoting about the governor sleeve l2, lowers the piston valve I4 50that pressure fluid is admitted to the underside of the power piston is.The piston l5 then rises to increase the eflective value of theresistance 1 and thus to decrease the excitation current and the outputof the generator.

If desired the governor 34 may control, as shown in Fig. 6, a separatepiston valve for the powerv piston instead of acting on the lever of theengine governor or may even, as shown in Fig. 7, control a separateresistance 40 in the excitation circuit oi the main generator. II it isdesired to limit the speed of the ciated resistance 6 maintain thetorque on said engine applied there-'- torque to said vehicle to a valuebelow cm: the controller ill may be set so, that some or the resistancesections remain in circuit. For example. it this controller is set atthe step m the'maximum speed which can be attained by the vehiclecorresponds to the value of v at the point of intersection of the curvesm and W in Figure 2. The controller iii in conjunction with its assothusserves not only as the starting controller for the vehicle but also as aconvenient means for limiting the maximum speed the vehicle reachesunder the control of the automatic gear.

It will be apparent. that the control gear can. I

the value of the full be adjusted to vary torque at which it is desiredto work the Diesel engine by adjusting the tension of the spring 01. theengine governor or by i/arying the cut-oi! positions of the piston'valveor in any other suitable manner.

It will be appreciated that the above description is by way of exampleonly and that modiilcations may be made within the scope of theinvention.

I claim:

1. A vehicle comprising an engine, a speed-responsive device operated bythe engine for maintaining the engine speed constant within apredetermined range, a generator driven by" said engine having a motorconnected thereto for propelling the vehicle, an excitation system forsaid generator including manually operated vehicle control means forvarying the excitation of said generator to gradually apply torque tosaid engine and start the vehicle, and means actuated in accordance withvariation in the speed of said engine for so varying the excitation ofsaid generator as to maintain the torque applied to said engine by themanipulation of said manually operated control means substantiallyconstant under varying operating conditions of the vehicle.

2. A vehicle comprising an engine, a generator driven by said enginehaving a motor connected thereto ior propelling the vehicle, anexcitation system for said generator including manually operated controlmeans for varying the excitation of said generator to apply said engine,aspeed-responsive device operated by said engine. and means actuatedthereby for so varying the excitation of said generator as to to by themanipulation of said manually operated control means substantiallyconstant under varying operating conditions 01 the vehicle.

3. A vehicle comprising an engine, a speedresponsive device operated bythe engine ior maintaining the engine speed constant within apredetermined range, a generator driven by .said'engine having a motorconnectedthereto for propelling the vehicle, an excitation system forsaid generator including variable resistance for varying the excitationof said generator, manually operated vehicle control means ior varying aportion oi said resistance to gradually apply torque gradually to,

ditions of the vehicle.

engine and start the vehicle, and

means actuated in accordance with variation in the speed or said enginefor so varying another portion or said resistance as to maintain thetorque applied to said engine by the manipulation of said manuallyoperated control means substantially constant under varying operatingconditions oi! the vehicle.

4. A vehicle comprising an engine, a speed-re- 'sponsive device operatedby the engine for maintaining the engine speed constant within apredetermined range, a generator driven by said engine having a motorconnected thereto for propelling the vehicle, an excitation system forsaid generator including manually operated vehicle control means forvarying the excitation of said generator to gradually applytorque tosaid engine and start the vehicle and including also resistance forvarying the excitation of said generator, means actuated in accordancewith variation in the speed or said engine for regulating saidresistance, and means associated therewith responsive to the currentthrough said motor to prevent decreasing current exceeds a predeterminedvalue to thereby prevent the tractive eiiort developed by said motorfrom exceeding a value which would cause slippage of the driving wheelsor the vehicle.

5. A vehicle comprising an engine, a speedresponsive device operated bythe engine for maintaining the engine speed constant within apredetermined range, a generator driven by said engine having a motorconnected thereto for propelling the vehicle, an excitation system forsaid generator including manually operated vehicle control means for,varying the excitation of said generator to gradually a'pply torque tosaid engine and start the vehicle, means actuated in accordance withvariation in the speed or said engine for varying the excitation of saidgenerator to maintain substantially constant the load applied thereto bythe manipulation of said manually operated control means, and meansresponsive to the speed of the vehicle associated with said excitationsystem for reducing the power output of the generator when the speed o!said generator including manually operated vehicle control means forvarying the excitation of said generator to graduallyapply torque tosaid engine and start the vehicle, a resistance capable of being put insaid excitation'system, and means actuated upon a decrease in the speedof said engine for putting at least applied to the engine by themanipulation of said manually-operated means to be maintainedsubstantially constant under varying operating consaid resistance whensaid a part of said resistance in the excitation system to cause thetorque.

